Clasp

ABSTRACT

The invention relates to a lever structure of clasps such as spring ring clasps or lobster claw clasps. 
     The clasp includes a substantially annular clasp body cut at one end to have a cut-away portion, an open/close member inserted inside the clasp body such as to slide in directions to open and close the cut-away portion, and a lever integrally formed with the open/close member such as to protrude outwards from the clasp body. The lever includes a neck portion that passes through a slit of the clasp body, and a lever body with a grip surface provided to a distal end of the neck portion such as to extend in a direction orthogonal to open/close sliding directions of the open/close member. The grip surface has a width that is set longer than a cross-section diameter of the clasp body.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a lever structure of clasps called spring ring clasps or lobster claw clasps.

2. Description of the Related Art

Spring ring clasps used for connecting chains such as necklaces are small, and yet, it is necessary to open an open/close member thereof, with a finger holding the lever of the open/close member, against the force of a spring that biases the clasp in a closing direction.

However, the lever is formed uniformly with the open/close member and thus small, or thin, having the same thickness as that of the open/close member, providing only a small contact area with a finger or a nail when operating the lever, because of which there was a risk that the finger might be hurt or the nail might be damaged.

In particular, since the spring ring clasp is operated with hands on the back of the neck, the shortcoming was that it was not easy to use not only for elderly or physically challenged people but also for people with long nails or artificial nails.

Another structure is known in which a metal bead is screwed to the lever. However, the structure is complex, and since the lever has substantially the same width and thickness, the above problem is not resolved.

A spring ring metal clasp according to Japanese Registered Utility Model Publication No. 3112368 is also known.

This spring ring metal clasp is formed by:

a tubular annular ring having a partially cut-away portion, a notch in an outer circumference thereof slightly away from one end of the cut-away portion, a U-shape ring on the outer circumference thereof slightly away from the notch to be connected with one end of a chain or a cord-like member, and a stopper in the tubular interior of the ring slightly away from the other end of the cut-away portion;

a core portion having a lever formed by processing a plate material such as to protrude from the notch and to be movable inside the tubular annular ring, and disposed such as to protrude from one end of the tubular annular ring to close the cut-away portion; and

a coil spring accommodated in the tubular annular ring and biasing the core portion in a direction in which the core portion closes the cut-away portion.

However, while the lever that is enlarged by processing a plate material is widened along the extending direction of the core portion, the lever is positioned such that its plate thickness part faces the wide surface of the U-shaped ring, and so there was the same conventional drawback when operating to open and close the core portion.

Therefore, when operating the lever with fingers bridging across the U-shaped ring and the lever, the finger is held on the lever in an area that is just a surface area portion of the plate thickness thereof, i.e., the finger is not held on the wide surface of the lever, and so the above problem associated with operability is not resolved.

The problem with this lever is found not only with the above-described spring ring clasp, but also with the lever used for operating other clasps such as a lobster claw clasp.

[Patent Document 1]

Japanese Registered Utility Model Publication No. 3112368

SUMMARY OF THE INVENTION

In view of the above circumstances, the main object of the present invention is to provide a lever for clasps that is easy to use for elderly or physically challenged people or for people with long nails or artificial nails, by making the area of a grip surface extending in a direction orthogonal to the direction in which the lever is operated wider than the width of the clasp body, since this grip surface makes contact with an operator's finger.

The invention provides a clasp, including a substantially annular clasp body cut at one end to have a cut-away portion, an open/close member inserted inside the clasp body such as to slide in directions to open and close the cut-away portion, and a lever integrally formed with the open/close member such as to protrude outwards from the clasp body, wherein the lever includes a neck portion that passes through a slit of the clasp body, and a lever body with a grip surface provided to a distal end of the neck portion such as to extend in a direction orthogonal to open/close sliding directions of the open/close member, the grip surface having a width that is set longer than a cross-section diameter of the clasp body.

According to the present invention, as described above, the grip surface of the lever body can be oriented in a direction orthogonal to the open/close direction of the open/close member, thereby making the contact area with an operating finger wider, and allowing easy operation of the lever.

Accordingly, the lever is easy to use not only for elderly or physically challenged operators but also for people with long nails or artificial nails because the nails are not likely to be damaged, the lever thus being extremely useful.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a clasp according to a first example;

FIG. 2 is a side view showing an example of use of the clasp;

FIG. 3 is a sectional view explaining a wide surface of the lever body of the first example;

FIG. 4 is a side sectional view of a clasp according to a second example;

FIG. 5 is a plan view of FIG. 4;

FIG. 6 is a sectional view explaining a wide surface of the lever body of the second example;

FIG. 7A is a side view and FIG. 7B is a front view of a primary product of an open/close member with a lever;

FIG. 8A is a side view and FIG. 8B is a front view of a finished product of the open/close member with a lever with its neck portion twisted;

FIG. 9A is a side view and FIG. 9B is a front view of an open/close member with a lever with a thin neck portion;

FIG. 10A is a side view and FIG. 10B is a front view of a lever forming part formed by bending a wire;

FIG. 11A is a side view and FIG. 11B is a front view of a lever formed by twisting a neck portion of the lever forming part of FIG. 10;

FIG. 12A is a front view of a lever provided with dot-like projections, FIG. 12B is a front view of a lever provided with linear projections, FIG. 12C is a front view of a lever provided with a hole, and FIG. 12D is a side view of an open/close member with a lever provided with a buffer part;

FIG. 13 is a partially cut-away side view showing an example of a lobster claw clasp; and

FIG. 14 is a side view showing a conventional lobster claw clasp.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention has realized a safe clasp with excellent operability by making a grip surface of a lever disposed in a direction orthogonal to the open/close direction of an open/close member so as to increase the contact area with an operating finger.

Preferred embodiments of the clasp according to the present invention will be hereinafter described with reference to the attached drawings.

FIRST EXAMPLE [Spring Ring Clasp]

In the first example (Example 1), the clasp according to the present invention is applied to a spring ring clasp.

The spring ring clasp 1 shown in FIG. 1 and FIG. 2 includes a cut-away portion 3 that is cut at one end of a hollow ring 2 to provide an entrance, a slotted hole slit 2 a extending from near one end of the cut-away portion 3 along the hollow ring 2 a distance corresponding to a stroke length of a lever 8, an annular ring (or U-shaped ring) fixed grip 4 on an outer circumference of the hollow ring 2 to be connected to one end of a chain or code-like member, and a stopper 5 provided in the tubular interior of the hollow ring 2 slightly away from the other end of the cut-away portion 3.

[Open/Close Member]

An open/close member 7 is made of a metal bar-like member of a circular arc shape capable of sliding inside the hollow ring 2, the lever 8 protruding outwards from a midway position thereof.

The open/close member 7 is inserted such as to be movable forward and backward at one end of the cut-away portion 3 of the hollow ring 2 through the slit 2 a so as to open and close the cut-away portion 3.

The rear end of this open/close member 7 engages with a distal end of a coil spring 6, which bends in a circular arc shape. The other end of the coil spring 6 engages with the stopper 5 near the other end of the cut-away portion 3 of the hollow ring 2, the stopper being a projection formed inside the hollow ring 2.

When the open/close member 7 is slid in a direction to open the cut-away portion 3 against the biasing force of the coil spring 6, the repulsive force of the coil spring 6 urges the open/close member 7 in a direction to close the cut-away portion 3.

[Lever]

The lever 8 consists of a neck portion 9 protruding from a midway position of the open/close member 7 and a lever body 10 formed at the distal end of the neck portion 9.

The neck portion 9 protrudes outwards through the slit 2 a from the hollow ring 2 that accommodates the open/close member 7. It is shorter than the width of the slit 2 a so that it can move forward and backward along the slit 2 a.

It is preferable, in terms of producibility, to set the length of the neck portion 9 to be equal to or smaller than the width of the open/close member 7. However, the neck portion 9 can be longer than the width of the open/close member 7, as long as it is slightly shorter than the width of the slit 2 a. This is because what is necessary is to allow the neck portion 9 to pass through the slit 2 a outwards as well as to slide forward and backward along the slit 2 a.

The lever body 10 is provided with a grip surface 10 a that is oriented in a direction substantially orthogonal to the directions in which the open/close member 7 slides to open and close, i.e., in the illustrated example, in the direction in which the open/close member 7 extends. The grip surface 10 a has a length w1 that is wider than the diameter w2 of a cross section of the hollow ring 2 (see FIG. 3).

Here, the width and height setting of the grip surface 10 a is such that it has a sufficient contact area so as not to damage an operating finger or nail.

The shape of the grip surface 10 a is not limited to the circular configuration shown in the drawing but it may be oval or geometric configuration or any other shapes.

The grip surface 10 a need not be solid but may be frame-shaped or provided with a hole.

With the spring ring clasp 1 having the above structure, the lever 8 is pulled towards the fixed grip 4 with fingers held on the grip surface 10 a of the lever body 10 and on the wide surface of the fixed grip 4 opposite the grip surface 10 a, so as to slide the open/close member 7 in the opening direction to open the cut-away portion 3.

At this time, the grip surface 10 a of the lever body 10 of the lever 8 makes contact with the user's finger, and since the contact area is large, operation is easy and the finger or nail is not likely to be damaged.

SECOND EXAMPLE

The spring ring clasp 1 according to the second example (Example 2) shown in FIG. 4 and FIG. 5 has an open/close member 7 and a lever 8 formed by punching a metal plate.

The structure of the spring ring clasp 1 in this case is similar to that of Example 1, and so the same elements are given the same reference numerals and the description thereof will be omitted.

In this example, a metal plate is punched to produce a primary product shown in FIG. 7 consisting of a circular arc-shape open/close member 7 with a square cross section and a lever forming piece 8′.

Here, a grip surface 10 a′ that will form a lever body forming piece 10′ and a neck portion forming piece 9′ of the lever forming piece 8′ are formed as an integral surface.

This primary product is bent to turn substantially 90° around the neck portion forming piece 9′ as an axis, so that, as shown in FIG. 8, the lever body forming piece 10′ is twisted substantially 90° relative to the direction in which the open/close member 7 extends, whereby the lever 8 is complete.

If, twisting the neck portion forming piece 9′ increases its diameter, it may be made thinner by applying pressure using a press or the like.

Thereby, as shown in FIG. 6, the grip surface 10 a of the lever body 10 has a width w1 longer than the diameter w2 of the cross section of the hollow ring 2.

FIG. 9 shows another example of the neck portion 9, which has a smaller thickness than that of the open/close member 7 and lever body 10 so as to make the bending work easier.

FIG. 9A shows a primary product consisting of the open/close member 7 and the lever forming part 8′, and FIG. 9B shows a finished product with the twisted neck portion 9.

FIG. 10 and FIG. 11 show a different example, which has an open/close member 7 and a lever 8 formed by bending a wire.

FIG. 10 shows that a single wire is bent in the same plane continuously to form a primary product consisting of a circular arc-shape open/close member 7 and a lever forming part 8″.

That is, the open/close member 7 consists of a pair of front and back open/close member forming parts 7 a, 7 a that are formed by bending both ends of the wire in a circular arc shape having the same radius of curvature.

The lever forming part 8″ consists of a pair of neck portion forming parts 9 a″, 9 a″ standing substantially vertically and extending linearly in close contact with each other between the pair of open/close member forming parts, and a lever body forming part 10″ bridging across the pair of neck portion forming parts 9 a″ at the top end thereof, extending annularly from one to the other of the neck portion forming parts 9 a″.

Therefore, the pair of neck portion forming parts 9 a″, 9 a″ is twisted therearound integrally with the lever body forming part 10′ to turn 90° and to stretch so that they are thinner to have substantially the same width as that of the open/close member 7, whereby the neck portion 9 and the lever body 10 shown in FIG. 11 are formed.

If, bending the neck portion 9 increases its diameter, it may be made thinner using a press or the like.

In this example, the part surrounded by the frame of the lever body 10 makes a grip surface 10 a.

The lever body 10 has the grip surface 10 a that makes contact with a finger or a nail; therefore, the grip surface 10 a may undergo various processing steps.

To give an example, the grip surface 10 a may be formed with dot-like or linear projections 10 b or grooves as shown in FIG. 12A or FIG. 12B to prevent slippage when it makes contact with a finger or a nail.

Alternatively, a hole 10 c may be drilled in the grip surface 10 a of the lever body 10 as shown in FIG. 12C.

Furthermore, rubber 10 d may be passed through the hole 10 c as shown in FIG. 12D so as to make the wide surface of the lever body 10 a rubber surface to provide a buffer function.

THIRD EXAMPLE

FIG. 13 shows a third example (Example 3) that is applied to a clasp 11 called a lobster claw clasp.

Conventionally, as shown in FIG. 14, a lobster claw clasp 21 is made up of a lobster claw clasp body 22 having a hollow base part 22 a with an open front and back to form a slit 23, with a substantially three-quarters circular frame extending from one to the other end of the base part 22 a with a cut-away portion S, and an open/close member 27 inserted inside the base part 22 a of the lobster claw clasp body 22 and pivotally supported in a middle portion so as to make engagement with the distal end of the frame such as to be capable of opening and closing.

The open/close member 27 is pivoted to open and close between a close position where it is retained by the distal end of the lobster claw clasp body 22 with the pivoting position P as a fulcrum, and an open position (indicated by a chain line in the drawing) where it is separated from the distal end of the lobster claw clasp body 22. It is biased toward a closing direction by a spring (not shown).

To the rear end of the open/close member 27 is formed a lever 28 integrally for open/close operation of the open/close member 27, such as to protrude from the slit 23 of the base part 22 a.

Conventionally, the lever 28 extends continuously from the open/close member 27 that is fitted in a groove formed to the base part 22 a, and therefore it has the same width as that of the open/close member 27, i.e., the contact area with a finger is small.

The clasp 11 according to Example 3 shown in FIG. 13 is made up of similar components as those of the clasp 21 shown in FIG. 14 such as a lobster claw clasp body 12, its base part 12 a, and a slit 13, except for the lever 28.

The lever 18 provided to the open/close member 17 consists of a neck portion 19 and a lever body 20.

Here, similarly to Example 2, the neck portion 19 is twisted substantially 90° so that a wide surface 20 a of the lever body 20 is disposed in a direction orthogonal to the direction in which the open/close member 17 slides (pivots) to open and close. Alternatively, instead of twisting the neck portion, the lever body 20 may be formed preliminarily so that its wide surface is directed in a direction orthogonal to the pivoting direction of the open/close member 17.

Thereby, when operating the lever 18, the wide surface 20 a of the lever body 20 is pressed with a finger or a nail, i.e., as the contact area is made larger, the finger or nail is not likely to be damaged.

While a spring ring clasp and a lobster claw clasp are described as clasps in the above Examples, the invention may be applied to other clasps such as hooks.

The present invention is not limited to accessories such as necklaces and can be applied to clasps used for straps attached to a mobile phone or a camera, i.e., the application of the invention should not be limited to a particular purpose.

It should be understood that various other designs and modifications are possible without departing from the sprit and scope of the invention. 

1. A clasp comprising: a substantially annular clasp body cut at one end to have a cut-away portion; an open/close member inserted inside the clasp body such as to slide in directions to open and close said cut-away portion; and a lever integrally formed with the open/close member such as to protrude outwards from the clasp body, wherein the lever includes a neck portion that passes through a slit of the clasp body, and a lever body with a grip surface provided to a distal end of the neck portion such as to extend in a direction orthogonal to open/close sliding directions of the open/close member, the grip surface having a width that is set longer than a cross-section diameter of the clasp body.
 2. A clasp according to claim 1, wherein the open/close member and a lever forming piece are integrally formed from a flat metal plate by punching; the lever forming piece is made up of a neck portion forming piece protruding substantially from a center of said open/close member and a lever body forming piece integrally formed to an upper part of the neck portion forming piece; and the neck portion and the lever body are formed by turning the neck portion forming piece with the lever body forming piece substantially 90° around said neck portion forming piece as an axis relative to the open/close member.
 3. A clasp according to claim 1, wherein the open/close member and a lever forming part are made of a single wire; the open/close member is made up of a pair of front and back open/close member forming parts that are formed by bending both ends of the wire in a circular arc shape having the same radius of curvature; said lever forming part is made up of a pair of neck portion forming parts standing up substantially vertically and extending linearly between said pair of open/close member forming parts in close contact with each other, and a lever body forming part bridging across the neck portion forming parts at an upper end of the neck portion forming parts extending annularly from one to the other of the neck portion forming parts; and the neck portion and the lever body are formed by turning said pair of neck portion forming parts with the lever body forming part substantially 90° around the pair of neck portion forming parts as an axis relative to the open/close member.
 4. A clasp according to any one of claims 1 to 3, wherein the clasp comprises: the cut-away portion formed by cutting one end of a hollow ring to provide an entrance; a slotted hole slit extending from near one end of the cut-away portion along the hollow ring a distance corresponding to a stroke length of the lever; a fixed grip fixed to an outer circumference of said hollow ring and having a hole in a center thereof; a stopper provided in a tubular interior of the hollow ring slightly away from the other end of said cut-away portion; and a spring inserted in the tubular interior of the hollow ring such as to be interposed between the stopper and the open/close member to bias the open/close member in a locking direction.
 5. A clasp according to claim 4, wherein a grip surface formed by the fixed grip and the grip surface of the lever body are arranged opposite each other.
 6. A clasp according to claim 1, wherein the clasp comprises: a hollow base part with an open front and back to form a slit; a circular-arc shaped frame extending integrally from one end of the base part and provided with the cut-away portion so that there is a gap between the frame and the other end of the base part; and the open/close member inserted inside said base part and pivotally supported in a middle portion thereof to said base part, one end of the open/close member protruding from said base part to openably close said cut-away portion and to be able to engage with a distal end of said frame, the other end of said open/close member being formed with the neck portion and the grip surface that protrude outwards from the slit of said base part. 